Previously, there had been no quantitative way to measure the effect of exercise on performance without actually engaging in exercise, stretching your limits and observing changes in performance. Performance, during exercise, is typically related to skills, muscle development and respiratory muscle endurance, the latter of which contributes to when an athlete will become breathless and need to stop.
The present invention provides a predictor of respiratory muscle endurance without the need to engage in the traditional exercise activity and without the need to stretch performance limits, and it can be used as an indicator showing corresponding improvements or declines in exercise or athletic performance. The present invention quantifies respiratory muscle endurance using the Fatigue Index Test (FIT) score. This score is closely coupled to performance and thus indicates changes in performance potential over time. Since FIT score indicates an individual's propensity to fatigue it may also help users predict the onset of maladies or declining health conditions in certain individuals earlier and more easily than using currently established methods.